Flat display devices are gradually becoming major display devices, and because the liquid crystal display panel of a flat display device does not illuminate itself, a backlight module is needed to illuminate it. Among various light sources used in flat display devices, a direct-type backlight module is widely used as the light source of a flat display device.
In a direct-type backlight module, a plurality of fluorescent tubes is arranged in parallel as the light source, in addition, a light plate can also be used as the light source. To be used as the light source, a light plate is easier to assemble and illuminates more uniformly than fluorescent tubes.
Please refer to FIG. 1A, which shows the backlight module 3 taking the light plate 4 as the light source in the conventional art. In the light of the direct-type backlight module 3 that takes the light plate 4 as the planar light source needed by the flat display device 2, the light plate 4 is installed in the aluminum light plate base 6, and the four sides of the light plate base 6 extend upward and horizontally outward to form the side frame 602. By the side frame 602 that extends horizontally outward, the diffusing plate 8, the optical material (including diffusing film, enhancing film and protective film) 10 and the LCD panel 11 dispose on the light plate base 6. At last, the upper fixing frame 12 is installed to form the flat display device 2.
Please refer to FIG. 1B, however, generally the four sides of the light plate 4 are a non-illuminating region 4A, thus the actually effective illuminating region 4B is smaller than the overall size of the light plate 4. In the conventional installment, the light plate 4 must be put upon the light plate base 6, thus the side frame 602 formed by extending the four sides of the light plate 6 outward cannot wrap the non-illuminating region 4A at the four sides of the light plate 4, which makes the width (D) of the ineffective region to include the widths of the non-illuminating region 4A and the side frame 602. Therefore, the width (D) of the ineffective region at the sides of the flat display device 2 and the overall size of the backlight module increase, and a larger fixing frame 12 is needed to cover the ineffective region, hence increasing the material cost of the fixing frame 12. In addition, if there is a need to disassemble the flat display device 2 that is already assembled, each structural layer must be disassembled in sequence for taking out the malfunctioned light plate 4, resulting inconveniences while replacing the light plate 4.
Therefore, the main object of the present invention is to provide a structure of a backlight module, for solving the above problems by using the different structure and assembling way.